<?php
$allCategories = $soap->call( $session_id, 'catalog_category.tree');
$root_children = $allCategories['children'];
// echo print_r($allCategories['children']);

// $cat_etronix = $soap->call ($session_id, 'catalog_category.info', 7);
// $children = $cat_etronix['children'];
// echo print_r($children);
$children = $root_children[1]['children'];
$len_category = sizeof($children);
//echo $len_category;
?>